Why do men fear women?

Much of violence against women, children, minorities, etc... is learned when a person is a child. The person tends to learn such abhorrent behavior from a parent or other relative in position of power (grandfather, uncle, brother who is in charge of the family, etc...).

They know, John, that we males are fundamentally unnecessary in the increasingly feminized world. The purpose of Woman, after all, is to take care of Man, while the purpose of Man is to carry heavy objects

The latter task increasingly amenable to wheeled machinery

Violence toward others stems from disdain. It can be against animals, people, things, even ideas.

Better to study violent behavior than to simply say that violence toward women is rooted in hatred of the female species. It's much more complex than that.

Why is nobody talking about violence from women, directed towards men?

It is usually quite expensive, but worth every penny, IMO.